Add LowerCaseStringConverter.cs.

svn path=/trunk/mcs/; revision=53009

mcs/class/System.Web/System.Web.dll.sources

@@ -97,6 +97,7 @@ System.Web.Configuration_2.0/HttpModuleAction.cs
 System.Web.Configuration_2.0/HttpModuleActionCollection.cs
 System.Web.Configuration_2.0/HttpModulesSection.cs
 System.Web.Configuration_2.0/HttpRuntimeSection.cs
+System.Web.Configuration_2.0/LowerCaseStringConverter.cs
 System.Web.Configuration_2.0/IRemoteWebConfigurationHostServer.cs
 System.Web.Configuration_2.0/MembershipSection.cs
 System.Web.Configuration_2.0/NamespaceCollection.cs